An Analytical Approach of Modelling Friction Stir Welding

AbstractA simple model for torque in friction stir welding is developed, based on a sliding/sticking condition in the contact interface, correlating the fundamental response variables temperature and axial force to torque. The model is validated by experiments using a special test rig enabling the precise measurement of the response variables. From the measured torque and axial force the friction coefficient μf is calculated and analyzed. It is observed that μf increases with decreasing rotation speed and drops with abrupt step-ups of the plunge depth. μf is found to mainly vary in the range of 0.3-0.4

In-Process Deformation Measurement of Thin-walled Workpieces

AbstractDuring the finish milling process of thin-walled workpieces, deformations occur due to the mechanical and thermal influences. The measuring method outlined in this publication allows an accurate assignment of these deformations to their respective cause in size and form, due to the high temporal and spatial resolution of the used optical measurement system. Furthermore, dividing the dis-placement into its mechanical and thermal proportion allows a fully decoupled validation of process models. Especially the simula-tion results of thermal models, which are mainly validated by measured temperature fields, can be further ensured

A Method for the Prediction of Process Parameters for Minimal Distortion in Welded Frame Structures Using a FE-simulation

AbstractWelded frame structures are often subject to unintended distortions due to the thermal joining process. In order to precisely quantify and reduce the distortion of welded frame structures using Finite Element (FE) simulation, a fast and reliable method is required, especially for industrial applications. This paper presents a methodical, simulation based and time optimised framework for the prediction of appropriate process parameters for minimal component distortion of complex welded frame structures by means of e.g. a variation of the process parameters or the weld seam sequences. To achieve a minimal distortion of the final structure, different optimisation algorithms will be used in combination with a database

Laser Intensity as a Basis for the Design of Passive Laser Safety Barriers – A Dangerous Approach

AbstractModern laser beam sources provide radiation with high output power and brilliance. Additionally, innovative laser system technology enables the deflection of the laser into every direction. These developments depict new aspects in laser safety. On the one hand, there is no standard design approach for laser safety barriers and, on the other hand, no practical database of resulting protection times is available. A prototype test rig was built up, which allows the determinationof the protection time of different passive safety barriers. By experimental investigations, a process model for single steel sheets was established, which provides a relation between the applied process parameters and the protection time of the safety barrier. Within the conducted investigations, the laser power and the spot diameter were varied, whereas former investigations only considered the total laser intensity. The presented results show the influence of the varied parameters on the protection time and provide a first database, which will be extended within further investigations

Experimental and Numerical Analysis of the Surface Integrity resulting from Outer-Diameter Grind-Hardening

AbstractBesides conventional heat treatment operations, an innovative approach for surface hardening is the grind-hardening process. During this process the dissipated heat from grinding is used for a martensitic phase transformation in the subsurface region of machined components. Additionally, compressive residual stresses are induced in the grindhardened surface layer. However, for the implementation of grind-hardening into industrial production extensive experimental tests are required to achieve iterative results of hardening depth. This paper focuses on the identification of parameter sets for a sufficient grind-hardening in outer-diameter grinding. On the one hand, grinding tests were conducted supported by metallographic investigations; on the other hand, a finite-element-based model was used to predict the surface integrity resulting from grind-hardening

Verification of structural simulation results of metal-based additive manufacturing by means of neutron diffraction

AbstractMetal-based additive processes are characterized by numerous transient physical effects, which exhibit an adverse influence on the production result. Hence, various research approaches for the optimization of e. g. the structural part behavior exist for layered manufacturing. Increasingly, these approaches are based on the finite element analysis to be able to understand the complexity. Hereby it should be considered that the significance of the calculation results depends on the quality of modeling the process in the simulation environment. Based on a selected specimen, the current work demonstrates in which way the numerical accuracy of the residual stress state can be analyzed by utilizing the neutron diffraction. Thereby, different process parameter settings were examined

Powder-Bed Based 3D-Printing of Function Integrated Parts

Mechanical Engineerin

Simulation Models for 3D Inkjet Printing – Material and Process Design

Due to the ability to produce complex parts with no need for pre-tooling, Additive Layer Manufacturing (ALM) is a future technology with 3D inkjet printing being one of them. The latter is based on the polymerization of a liquid dispensed into a powder bed. However, the special challenges which have to be met here are to increase product quality such as tensile strength and density on a repeatable base. Consequently multi-scale simulation models were developed to support material researchers as well as users of the technology in their daily work and therefore to contribute to process stability and material reliability of 3D printers and their products.Mechanical Engineerin

Multi-scale Modelling Approach for Contributing to Reduced Distortion in Parts Made by Laser-based Powder Bed Fusion

Within this paper, a control volume-based multi-scale approach for heat input modelling in laser-based powder bed fusion of metals is described. Thereby, the Rosenthal equation is used to analyse beam-powder interaction for a single laser track. Based on both the Rosenthal results for melt pool dimensions and experimentally determined melt pool depth, a single layer model is developed. Results for the temperature field, gathered by applying the single layer model, serve as data for validating the control volume-based approach on the build-up scale. Finally, a case study with a turbine blade delivers the proof-of-concept for the applied modelling approaches, because process-related distortions are reduced by more than 40% through pre-deforming the blade according to build-up simulation results